5-Substituted 1,3,4-thiadiazole-2-carboxaldehyde thiosemicarbazones

ABSTRACT

This invention relates to novel 5-amino, 5-alkanoylamino and 5nitro-1,3,4-thiadiazole carboxaldehydethiosemicarbazones. These compounds are useful as antibacterial or antifungal agents.

United States Patent Berkelhammer et al.

S-SUBSTITUTED l ,3,4-THIADIAZOLE-Z-CARBOXALDEHYDE THIOSEMICARBAZONES lnventors: Gerald Berkelhammer, Princeton;

Goro Asato, Titusville, both of NJ.

Assignee: American Cyanamid Company,

Stamford, Conn.

Filed: on. 31, 1973 Appl. No.: 411,574

Related US. Application Data Division of Ser. No. 300,640, Oct. 25, 1972, Pat. No. 3,794,665, which is a division of Ser. No. 92,908, Nov. 25, 1970, Pat. No. 3,725,396, which is a continuation-in-part of Ser. No. 767,004, Oct. ll,

[ Apr. 15, 1975 1968, Pat. No. 3,598,830.

[52] US. 260/302 D; 260/306.8 D [5]] Int. Cl. C07d 91/62 [58] Field oi Search 260/306.8 D, 302 D Primary Examiner-R. Gallagher Attorney, Agent, or Firm-Ernest Y. Miller [5 7] ABSTRACT 4 Claims, N0 Drawings SUMMARY OF THE INVENTION The present invention relates to novel thiadiazole' compounds, a method for their preparation and a method of use for controlling bacteria and fungi. particularly plant pathogenic bacteria and fungi. More particularly. the novel compounds of the invention have the formula:

wherein R is selected from the group consisting of amino. nitro and lower alkanoylamino and R. is selected from the group consisting of oxazolidinone.

In the preparation of the present compounds as shown in the flowsheets and examples hereinafter set forth three essential starting materials are used. The first of these is 5-nitro-l ,3,4-thiadiaZole-2- carboxaldehyde. the product of Examples 1 and 4, and described in the flow diagrams as compound (IV). The second is 5-amino-l ,3,4-thiadiazole-2-carboxaldehyde. the product of Example 3. identified ascompound (III) in the flow diagrams and 5-acetamido-l,3,4- thiadiazole-2-carboxaldehyde. the product of Example II and referred to in the flow diagrams as compound (XI).

In accordance with the invention and referring to flow diagram I. 5-nitro-l-,3,4-thiadiazole-2- carboxaldehyde (IV) can be preparedby oxidation of Z-methyl-S-nitro-l.3.4-thiadiazole (I) at high temperature. The reaction is preferably carried out in the presence of an inert organic solvent and employing an oxidizing agent such as, for example, selenium dioxide. Said compound (IV) may also be prepared from 5- thiadiazole-Z-carbo'xaldehyde l-amino-2 imidazolidinone or thiosemicarbazide. respectively." The reactions are preferably conducted in an alcoholic or aqueous-alcoholic medium at an elevated temperature. generally between about 70 and 115C. and under slightly acidic conditions. Mineral acids such as hydrocihloric and sulfuric acid are well adapted to use in these reactions.

Similarly, treatment of S-amino-l.3.4 thiadiazole-2- carboxaldehydev (III) (Flow Diagram II) or 5- acetamidol.3.4-thiadiazole-Z-carboxaldehyde (XI) (Flow Diagram III) with 'I-amino-Z-imidazolidinone. 3-amino-l-oxazolidinone or thiosemicarbazide. under :.acid conditions at an elevated temperature. yields respectively, the corresponding l-{I'(5-amino-l.3.4- thiadiazol-Z-yl)methylene]amino}-2-imidazolidinone (XII). 3-{[(5-amino-l.3,4-thiadiazol-2-yl)methylene]amino}-2-oxazolidinone (XV). 5- amino-.I.3.4- thiadiaz'olecarboxaldehyde thiosemicarbazone (XVII). and l-'{[(5-acetamidol ,3.4-thiadiazol-2-yl )methylene]amino} -2-imidazolidinone (XllI).3-{[(5- acetamidol .3.4-thiadiazol-2-yl )methylene]amino}-2- oxazolidinone -'(X IV).- and 5-acetamido-l.3.4-

thiadiazole-Z-carboxaldehyde thiosemicarbozone (XVI). I I

Cyclization of 5-nitrol ,3.4-thiadiazole-2- carboxaldehyde thiosemicarbazone (VII). (Diagram l). S-amino- I .3.4-thiadiazolecarboxaldehyde thiosemicarbazone (XVII). (Diagram II). and 5-acetamido-l.3.4-

thiosemicarbazone (XVI). (Diagram III). to the corresponding aminothiadiazoles can then be achieved by treatment of said thiosemicarbazones with an oxidative cyclizing agent such as ferric ammonium sulfate. ferric chloride or ferric sulfate. at an elevated temperature preferably be- (IV) or 5-acetamido-l.3,4-

thiadiazole carboxaldehydes (XI) are reacted with amino-l,3,4-thiadiazole-Z-carboxaldehyde (III) by forv quinaldine and acetic anhydride under acid conditions and high temperature the corresponding thiadiazol-Z-yl vinyl quinolines. (XX) and (XXI) respectively, are formed. However. the S-amino carboxaldehyde (III) does not undergo'the same reaction to form the corresponding S-amino vinyl quinoline. but rather. yields the S-acetamido vinyl quinoline (XXI) which is converted by acid hydrolysis to the 2-[2-(5-amino-l.3,4- thiadiazol-Z-yl)vinyl]quinoline (XXII), (Diagram III).

In Flow Diagram (II) it can be seen that S-amino-l- 3.4-thiadiazole-2-carboxaldehyde (Ill) may be ob tained by first refluxing p-nitrobenzaldehyde with 2- acetamido-5-methylthiadiazole in acetic anhydrife to obtain ,B-( S-acetamido- I ,3 ,4-thiadiazol-2-yl )-pnitrostyrene (Il)'and ozonizing such product in the presence of ethyl acetate to yield a crude product containing S-acetamido-l,3,4-thiadiazole-2- carboxaldehyde (XI) which may be hydrolyzed to 5- amino-1,3 ,4-thiadiazole-Z-carboxaldehyde (Ill) under acid conditions. If desired the 5-,acetamido-l.3.4- thiadiazoIe-Z-carboxaldehyde (XI) may also be obtained from S-amino-l .3.4-thiadiazolle-2- carboxaldehyde (III) by refluxing with acetic anhydride.

FLOW DIAGRAM III CONTINUED I cHaC-N I FeNH (so. -12n o' V E l l 'M l cna C-N s S NR XXIII The compounds of the present invention are useful as antibacterial and antifungal agents. They find utility in such areas as treatment of industrial process waters used for cooling equipment and in paper manufacture to control slimes. Generally about l to 500 ppm. of the compounds of the present invention are effective for this purpose. As indicated, these compounds are also useful for protecting fabrics. textiles. leather and the like as well as agronomic crops. both growing and harvested. from the deleterious effects of these organ isms.

in practice the compounds of the invention may be formulated with both solid and liquid diluents and applied in the form of dusts and sprays to the materials or plants for which protection is sought.

Dust formulations are generally prepared by admixing about 1 to percent by weight of active compound with a finely divided carrier such as kaolin. attapulgite. diatomaceous earth, tal c or the like can be applied with conventional dusting apparatus. For p'rotection of growing plants generally abouot V2 'lb. to 8 lbs. per acre of active ingredient is sufficient but somewhat higher rates may be employed if so desired.

Wettable powder formulations which are generally dispersed in an inexpensive liquid carrier, such as water or deodorized kerosene, for spray application. are usually prepared by admixing about 25 to 90 percent by weight of active ingredient with about 5 to 25 percent of a solid diluent. as described above with regard, to dust formulation; about l'to3 percent of a wetting agent and about 2 to 5 percent of a dispersant. For application to crops. the wettable powder is dispersed in water in sufficient amount to provide about lb. to 2 lbs. of active ingredient per I00 gallons of water and applied at the rate of about 100 to 400 gallons per acre.

DETAILED DESCRIPTION The following examples describe the prepa'ration'of the present compounds and tests as antibacterial and anti-fungal agents.

EXAMPLE 1 Preparation of S-Nitrol ,3.4-thiadiazole-Z-carboxaldehyde (IV) The compound Z-methyI-S-nitro-l.3,4-thiadiazole (l)-(0.73 g. or,5 mmolefand 0.55 g. (5 mmole) of selenium dioxide are mixed and heated until a highly exothermic reaction occurs. The mixture is cooled and extracted with methylene chloride. The extracts are dried and evaporated to drynessto give a red-brown liquid. which is the title compound; infrared spectrum (heat):

l700"(C=O), 1565 and 1355 (NO;;) cmf.

EXAMPLE 2 Preparation of B-( 5-Acetamido-l .3.4-thiadiazol-2-yl )-p-nitr0styrene (II) Preparation of 5-Amino-l,3.4-thiadiazole-2-carboxaldehyde (III) in 700 ml. of ethyl acetate, 20 g. (0.069 mole) of B-( S-acetamidol .3,4-thiadiazol-2-yl )-p-nitrostyrene is treated with ozone (4 percent G in 0 stream, 0.08 moles per hr.) at 30 to 35C. for 2 hours to give a tan-colored suspension. The reaction mixture is purged of ozone with nitrogen for 20 minutes. To this, 60 g. of sodium iodide in 40 ml. glacial acetic acid and 400 ml. of water are added which are followedby 80 g. of sodium thiosulfate in 800 ml. of water. The organic layer is separated after 500 ml. of ethyl acetate is added and V the aqueous layer further extracted with 400 ml. of

ethyl acetate. The extracts are dried over magnesium sulfate. filtered, and evaporated to give a yellow-brown sticky solid (20.5 g.). This material contains a mixture of p-nitrobenzaldehyde. and 5-acetamido-l,3,4- thiadiazole-Z-carboxaldehyde. This mixture is heated on a steam bath for 70 minutes with 19 ml. of concentrated hydrochloric acid and 20 ml. of glacial acetic acid. Evaporation of the acids under reduced pressure gives a yellow solid. which is treated with 300 ml. of 10 percent hydrochloric acid to dissolve the aminothiadiazole aldehyde and the mixture is extracted twice with 200 ml. volumes of ethyl acetate to remove pnitrobenzaldehyde. The aqueous acid phase is neutralized with sodium bicarbonate and then extracted with three 300 ml. volumes of ethyl acetate.'These latter extracts are combined and dried over magnesium sulfate and evaporated to give 2.3 g. of solid yellow product (-amino-l ,3,4-thiadiazole-2-carboxaldehyde; infrared A max. (Nujol): 1688 cm. (C=O), NMR (acetone d):, 1.83 \(NH and 0.04 A (-CHO).

In a similar run. liquid-liquid extraction of the final aqueous phase with ethyl acetate gives a total yield of 4.1 g. of 5-amino-l.3.4-thiadiazole-2-carboxaldehyde. melting point 155l57C. (dec.).

EXAMPLE 4 Preparation of 5-Nitro-1,3.4-thiadiazole-2-carboxaldehyde (IV) comes green. foams. and a brown-yellow solid appears.

The mixture is stirred for 30 minutes. filtered, and the insoluble solid washed with 5075 ml. portions of hot chloroform until no more color is removed. The filtrate is extracted with ether (2 times with 100 ml. volumes), with 100 ml. of benzene, and with 100 ml. of chloroform. These extracts give about 0.1 g. of 5-nitro-1.3.4- thiadiazole-2-carboxaldehyde. The hot chloroform washes yield 0.60 g. of S-nitro-l .3.4-thiadiazole-2- carboxaldehyde. These combined crude materials are dissolved in ether. filtered. and the filtrate evaporated to dryness to give 0.44 g. of purer title compound which is orange and exhibits a carbonyl band at about 1680-1700 cm? in the infrared; this material is semisolid.

EXAMPLE 5 Preparation of 3-{[(5-nitro-1.3 ,4-thiadiazol-2-yl )methylene ]-amino}- 2-oxazolidinone (V) A solution of 2.1 g. (0.013 mole) of 5-nitro-2- thiadiazolecarboxaldehyde in 15 ml. of 95 percent ethanol is added to a solution of 1.53 g. (0.015 mole) of 3-amino-2-oxazo1idinone in ml. of 95 percent ethanol. The resulting solution is treated with 2 drops of concentrated hydrochloric acid and heated for minutes on a steam bath. The yellow solid is collected and dried to give 1.1 g.. melting point 248250C.. of the title compound.

EXAMPLE 6 Preparation of 1-{[(5-nitro-1.3.4-thiadiazol-2-yl)methylene]-amino}- 2-imidazolidinone (V1) A solution of 1.8 g. (0.011 mole) of 5-nitro-l.3.4- thiadiazole-Z-carboxaldehyde in ml. of 95 percent ethanol is added to 40 ml. of a 0.33 M solution of 1- amino-Z-imidazolidinone in dilute sulfuric acid and the mixture heated on a steam bath. Water is added to the mixture until a clear solution is obtained and after 30 minutes of heating. it is cooled. The brown needles are collected and recrystallized from ml. of 67 percent aqueous ethanol to give 1.0 g. of yellow crystals. melt ing point 230232C. of the title compound.

EXAMPLE 7 Preparation of 5-Nitro-1'.3.4- -thiadiazole-2-carboxaldehyde thiosemicarbazone V11) 5G. (0.031 mole) of S-nitro-l.3,4-thiadiazole-2- carboxaldehyde is dissolved in 50 ml. of percent ethanol and 3.6 g. (0.04 mole) of thiosemicarbazide in 50 ml. of 50 percent aqueous ethanol and 5 drops of concentrated hydrochloric acid are added. The mixture is heated at 90-95C. for 30 minutes. cooled, and the red solid connected. The yield of the title compound. melting point 290C.. is 4.0 g.

EXAMPLE 8 Preparation of 2-Methyl-5-nitro-1.3.4-thiadiazole (l) A solution of 2.78 g. (0.024 mole) of 2-methy1-5- aminothiadiazole in 17.5 ml. of 48-50 percent fluoroboric acid is stirred at 0C while 1.67 g. (0.024 mole) of sodium nitrite, is added over 30 minutes. The mixture is stirred for 20 minutes at 0C. and then added dropwise to a vigorously stirred suspension of 4.9 g. of copper powder in a solution of 24.7 g. of sodium nitrite in 50 ml. of water at 25C. The mixture is stirred for 30 minutes. filtered. and the filter cake washed thoroughly with water. The combined filtrate and washings are extracted with three ml. volumes of benzene. The combined extracts are dried and evaporated under reduced pressure to give 1.75 g., melting point 54-55C.. of 2-methyl-5-nitro-1.3,4-thiadiazole.

EXAMPLE 10 Preparation of B-( 5-Aminol ,3 .4-thiadiazol-2-yl) -p-nitrostyrene A suspension of 5.0 g. of B-(5-acetamido-L34- thiadiazol-Z-yl)-p-nitrostyrene in 20 m1. of concentrated hydrochloric acid and 20 ml. of glacial acetic acid is heated to reflux temperature for 2 hours. The solid is collected. washed with ether. and dried to afford 4.4 g. of solid. This solid is washed with 25 ml. of 5 percent sodium bicarbonate solution and heated to 50-55C. until foaming stops. The solid is collected. washed with water and dried to give 0.81 g. of yellow B-( S-amino- 1 .3.4-thiadiazol-2-yl )-p-nitrostyrene. melting point 284C. (dec.).

EXAMPLE 1] Preparation of 5-Acetamido-1 .3,4-thiadiazole-2-carboxaldehyde (X1) A portion of 1.29 g. (0.01 mole) of 5-amino-l,3,4-

thiadiazole-2-carboxaldehyde is heated with 5 ml. of acetic anhydride at reflux temperature, cooled and evaporated to dryness. The yellow solid is washed with saturated aqueous sodium carbonate solution to afford 5-acetamido-1.3 ,4-thiadiazole-2-carboxaldehyde.

EXAMPLE 12 Preparation of l-{l( 5-Amino-l 3,4-thiadiazol-2-yl )methylene]- amino}-2-imidazolidinone (XII) The compound S-amino- 1 .3 ,4-thiadiazole-2- carboxaldehyde (1.29 g. or 0.01 mole) is reacted with 1-amino-2-imidazolidinone in the manner described in Example 6 to give l-{[(5-amino-l,3,4-thiadiazol-2- y1)methylene]-amino}-2-imidazolidinone, which is collected as a pale yellow solid.

EXAMPLE 13 Preparation of l- 5-Acctamidol ,3 ,4-thiadiazol-2-yl )-methylene]- amino}-2-imidazolidinone (XIII) To 171 g. (0.01 mole) of 5-acetamido-l,3,4- thiadiazole-2-carboxaldehyde in ml. of 95 percent ethanol is added to 40 ml. of 0.33M solution of lamino-2-imidazo1idinone in the manner described in Example 6 to give solid l-{[(5-acetamido-l.3,4- thiadiazol-Z-yl)methylene]amino}-2-imidazo1idinone.

EXAMPLE 14 Preparation of 3-{[ S-acetamidol ,3,4-thiadiazol-2-yl )methylene I- amino}-2-oxazolidinone (XIV) The compound 3-amino-2-oxazolidinone is reacted in cquimolar amounts witih 5-acetamido-1.3,4- thiadiazole-2-carboxaldehyde in the manner described in Example 5 to give 3-{[(5-acetamido-l.3.4- thiadiazol-Z-yl)methylene]amino}-2-oxazolidinone. which is collected as an off-white solid.

EXAMPLE 15 Preparation of 3-{[(5-Amino-1,3 ,4-thiadiazol-2yl )methylene amino}-2-oxazolidinone (XV) Equimolar quantities of 5-amino-1,3,4-thiadiazo1e-2- carboxaldehyde and 3-amino-2-oxazolidinone are reacted in the manner described in Example 5 to give 3- {[(5-amino-l ,3,4-thiadiazol-2-yl )methylene]amino}- 2-oxazolidinone, which is collected by filtration as a solid.

EXAMPLE 16 Preparation of S-Acetamidol ,3,4-thiadiazole-Z-carboxaldehyde thiosemicarbazone (XVI) S-Acetamido-l,3,4-thiadiazole-2-carboxaldehyde is reacted with an equimolar quantity of thiosemicarbazide in the manner described in Example 7 to give the above compound, which is collected by filtration as a EXAMPLE 17 Preparation of 5-Aminol ,3,4-thiadiazolecarboxaldehyde thiosemicarbazone (XVII) In 15 ml. of 95 percent ethanol, 1.29 g. (0.01 mole) of S-amino-l,3,4-thiadiazole-2-carboxaldehyde and 0.92 g. ofthiosemicarbazide are reacted in the manner described in Example 7 to give the above compound, which is collected by filtration as a solid.

12 EXAMPLE 18 Preparation of 2-Amino-5-(5-amino-l,3,4-thiadiazo1-2-y1)-1,3.4- thiadiazole (XVIII) The title compound is prepared in the manner described in Example 8 by cyclizing 2-amino-l.3.4- thiadiazole-Z-carboxaldehyde thiosemicarbazone and collecting the product as a solid.

EXAMPLE 19 Preparation of 2-Acetamido-5-(5-acetamido-1.3,4-thiadiazol-2-yl)- 1.3,4-thiadiazole (XIX) The compound 2-amino-5-( S-aminol ,3,4- thiadiazol-2-yl)-l,3,4-thiadiazole is refluxed with acetic anhydride for /2 hour, evaporated to dryness. and the remaining solid washed with saturated aqueous sodium carbonate to give the title compound.

EXAMPLE 20 Preparation of 2-[ 2-( 5-nitro-l .3 ,4-thiadiazol-2-yl )vinyl]quinoline EXAMPLE 21 Preparation of 2-[2-(5-acetamido-l,3,4-thiadiazo1-2-y1)vinyl]- quinoline (XXI) The title compound is prepared as described in Example 20 by reacting S-amino-l,3,4-thiadiazole-2- carboxaldehyde with quinaldine in the presence of acetic anhydride.

EXAMPLE 22 Preparation of 2-[2-(5-Amin0-1.3,4-thiadiazol-2-yl)vinyl]quinoline (XXII) The above compound is obtained by treating 1 g. of 2-[2-(5-acetamido-1,3,4-thiadiazol-2- yl)vinyl]quinoline with 5 ml. of concentrated hydrochloric acid in 5 ml. of glacial acetic acid for 2 hours on a steam bath and neutralizing the mixture with saturated aqueous sodium carbonate solution. The solid product is collected by filtration and washed with water.

EXAMPLE 23 The antibacterial activity of the compounds of the present invention is demonstrated by the following tests wherein test compounds are dissolved in deionized water in sufficient amount to provide ppm. of compound in the water. Test solutions are then sterilized and inoculated with a bacterial cell suspension of the test organism. The bacterial cell suspensions are 24 hour broth (0.1 percent dextrose-1.0 percent peptone) cultures that were inoculated with bacteria from 7-day Nutrient Agar Slants. After exposure for 24 hours, each test solution is treated with 10 percent by volume of a 1 percent dextrose-10 percent peptone broth. The

treated solutions are then incubated for 24 hours at rot of stone fruits; .S'temp/rvlimn sarcinaeforme, the 37C. and then examined for the presence or absence pathogen which incites leaf spot of legumes and Asperof bacterial growth. Determinations are made by turgillus niger, the saprophyte that degrades textiles, fabbidity readings. Solutions with no bacterial growth are rics, leathers, fruits and vegetables. subcultured to determine if the bacteria have been killed. Data are recorded as follows: 9 kill; stasis; EXAMPLE 0 no apparent effect. The antibacterial activityof the compounds of the Bacteria employed are Aerobacrer aemgenes, a gram present invention is further demonstrated in the follownegative organism used by the Paper Institute to evaluing tests wherein trypticase soy agar plates are preate slime control agents for paper mills. Stap/zylococcus 0 pared Containing 4 to 250 meg/ml. of test compounds. uureus, a gram positive common on the skins of man The plates stored at room temperature overnight and animals certain strains of which are pathogenic, then are inoculated with the desired cultures. After inand XanI/wmonas vesicatoria, a gram negative organoculation the plates are permitted to dry, then inverted ism which incites bacteriosisof tomatoes and peppers. and incubated for 24 hours at 37C. After the incuba- Data obtained are provided in Table l. l5 tion the plates are examined and growth or no growth TABLE I.

Compound Rate A. aerogenes S. aureus X; ves:l.eat:or;l.a.

N u w )l /|l\ 100 ppm. 9 9 9 s [CH3 N n N NJi II 100 ppm. 9 I 9 5 0 S s NHZ 'n l S ll 100 pp 9 5 9 2M 5 CH=N-NHC-NH2 EXAMPLE 24 determinations made by comparison with growth control plates. The results are recorded and reported below in Table II] as the minimum concentration (meg/ml.) required to prevent growth of the organism. Organisms employed are recorded below.

The antifungal activity of the compounds of the invention is demostrated by the following test wherein 7-10 day cultures of M. ji'ucticola, 14 day cultures of S. .s'arcinaeforme and 7 day cultures ofA. niger are separately washed from slants with deionized water and the suspensions filtered to remove large pieces of myce- GRAM POSITIVE BACTERIA llum. Two ml. of orange uice are added per liter of Abbreviation NAME spore suspension to facilitate germination. Opticular 40 l. B.c. Butillus Corvus vials are then partially filled with the individual suspen- 8 87/01/11,? .r hz lm II'I"H.\'.\' sions of test organism and a sufficient amount of aque- -,,,.f:., il, ii fflfi'f ous solution or suspension of test compound added to h lurm -qu m I 6. 5.1!. Slap/1) lm'uum rum-us rovide 100 m. thereof to the test vials. The vials are 7. 5.11. .S'trclmu'ut'cm' m/mimp p 8 Sf S I. placed on a tumbler and rotated for 24 hours to expose 4S 'GRAM NEGATIVE the organisms to the test compounds. At the end of a t 24 hour exposure period the suspensions are examined gt. Bunlmllu I'(I)mlii.\';'p!i 'a .c. Izlrc icric iiu cu: macroscopically. Data are recorded as percent of the 13' Pm rumwvflu I'm/Midi! spores that have not germinated and are reported be- .SUIISI HIIm'IIufi/lrI54'7;t'.till.t

10W. 16. S.g. Su/lgmneI/a eulliuur ml As indicated above the organisms used are Momlmm l7. St. v .Sulmmwllu l \plu l8. S. .Succhurm"yr-('5 cercrlsuu' fi'uc'ncola, the pathogen that incites American brown TABLE II Rate M A Compound ppm fructlcola sarcinaeforme nl'ger f j 100 100 100 02 s 3 M1 l 100 100 100 100 02N s CH3 

1. THE COMPOUND OF THE FORMULA:
 2. The comound in accordance with claim 1, 5-acetamido-1,3,4-thiadiazole-2-carboxaldehyde thiosemicarbazone.
 3. The compound in accordance with claim 1, 5-nitro-1,3,4-thiadiazole-2-carboxaldehyde thiosemicarbazone.
 4. The compound in accordance with claim 1, 5-amino-1,3,4-thiadiazole-2-carboxaldehyde thiosemicarbazone. 